The present disclosure describes subject matter that relates to closed loop systems that circulate a working fluid, with particular discussion about embodiments of a system that can utilize working fluids to operate one or more components (e.g., a pump) to improve efficiency and/or reduce parasitic losses.
Systems that generate power include closed loop systems that operate under principles of a Rankine Thermodynamic Cycle. These systems use thermal energy from a thermal source fluid to evaporate a working fluid, e.g., a low temperature boiling organic fluid. This process generates high pressure vapor. In conventional designs, the system directs the vapor to a turbine, or like device, that can operate a generator to generate electric power. The system can also cool and condense the vapor to liquid form. During operation, the system circulates the working fluid, in liquid form, for use in the evaporation and power generating stages of the design.
FIG. 1 illustrates a schematic diagram of an example of a conventional closed loop system 100. This embodiment includes a pump component 102, an evaporator component 104 (that utilizes a source fluid S), a power generating component 106, and a condenser component 108 (that utilizes a cooling medium C). The system 100 also includes a fluid circuit 110, typically a construction of fluid conduits (e.g., pipes, tubes, valves, etc.) that couple the components 102, 104, 106, 108 together. The fluid circuit 110 allows a working fluid F to circulate among the components 102, 104, 106, 108. In the example of FIG. 1, the working fluid F exhibits one or more set of working properties (e.g., a first set 112, a second set 114, a third set 116, and a fourth set 118), each set being configured to identify, for example, a pressure and a temperature of the working fluid F that circulates through the fluid circuit 110. The value of the working properties often correspond to phases (e.g., liquid, vapor, etc.) of the working fluid F.
For most closed loop designs, the system 100 is configured to continuously circulate the working fluid among the various stages (i.e. evaporation, power generation, and condensation). These configurations often employ a pump (e.g., pump component 102) that pressurizes the working fluid, in liquid form, prior to delivery to the evaporation and/or power generation stages. In many cases, the system will supply power to drive the pump from the generator. This feature, however, reduces the power from the system that would otherwise be available for use.